1. Field of the Invention
The present invention relates to a process for deodorization of a bad smell gas. More particularly, it relates to a process for deodorization using a combination of ozone and a wet washing device.
2. Description of the Prior Art
Heretofore, the system shown in FIG. 1 has been used for the conventional ozone deodorization.
In FIG. 1, the reference numeral (1) designates a bad smell gas; (2) designates a wash tower for washing the bad smell gas (1) with water; (3) designates a washing solution stored in the wash tower (2); (4) designates a pump for sucking the washing solution (3) to form a mist (5) in the wash tower (2); (6) designates a demister placed at the upper part of the wash tower (2); (7) designates a duct for feeding the gas (1) which is washed with water through the demister (6), into a detour type ozone reactor (8); (9) designates an ozonizer; (10) designates a diffuser for uniformly mixing the gas (1) in the duct (7) with an ozone-containing gas (11) obtained in the ozonizer (9) and the diffuser is connected to the duct (7) and (12) designates a treated gas which is deodorized in the system.
The operation of the system will be described.
The gas (1) is fed into the wash tower (2) wherein water soluble bad smell substances contained in the gas (1) are absorbed into the washing solution (3) as the mist (5) to be removed. Then, the bad smell gas (1) is passed through the demister (6) to remove the mist entrained in the gas (1) and it is fed to the duct (7). The washed gas (1) is uniformly mixed, in a moment, with the ozone-containing gas diffused from the diffuser (10) placed in the duct (7) and the mixed gas is fed into the ozone reactor (8). The mixed gas is passed through the detour passage in the ozone reactor (8) for a residence time of from at least several second to 1 minutes and the gas (1) is discharged as the deodorized gas (12).
The deodorizing system for the conventional deodorizing process has said structure whereby bad smell substances which can be removed by a water washing such as ammonia, lower fatty acid and lower amines are highly removed depending upon the washing condition. In the ozone reactor (8), the bad smell substrates such as nitrogen oxides methyl sulfide and dimethylamine which are reactable with ozone, are removed. However, bad smell substances such as hydrogen sulfide, methyl mercaptan and aromatic hydrocarbons have their reaction velocity constants of less than 10.sup.5 liter/mol.min. In the concentration of less than the ppm odor, their reactivities to ozone are remarkably low whereby most of the unreacted bad smell substances are discharged out of the system. The ozone-containing gas (11) added to the gas (1) is also discharged as the unreacted gas with the treated gas (12).
In the conventional ozone deodorizing process, the deodorizing effect for the other bad smell substances which are different from ozonizable substances such as ammonia, and the unreacted ozone is disadvantageously discharged. Moreover, the washing solution which contains water soluble bad smell substances absorbed by recycling through the wash tower, is directly discharged or is discharged after a dilution. The water containing bad smell substances is drained. This is not a satisfactory deodorization. The discharged water can be further deodorized before the drainage. However, the other apparatus must be connected and this increase the cost for the treatment.